A comparative study of the pyrolytic behavior, product properties, and environmental-economic performance of old corrugated containers recycling using pyrolysis and catalytic graphitization

The pyrolysis technology has shown the potential to effectively convert complex organic matter into high-value-added products. The pyrolysis and iron-catalytic graphitization processes were investigated with a view to converting old corrugated containers into valuable products, with a particular focus on pyrolytic behavior, kinetics and environmental-economic performance. Activation energy of dehydration, devolatilization, and carbonization stages determined by Coats-Redfern method were 162.721 kJ/mol, 173.679 kJ/mol and 245.753 kJ/mol, respectively. During the pyrolysis reaction, as the temperature increased and the H/C atomic ratio declined, the solid char underwent a gradual polymerization process, forming a large aromatic structure. At 800 °C, the hydrogen yield was 4.64 mmol/g and the resulting char was nonporous with a surface area of 32.06 m²/g. Catalytic graphitization method promoted deoxygenation and activation of carbon-hydrogen bonds, resulting in the formation of porous graphitic char. The graphitic char exhibited a high surface area of 292 m²/g and a high graphitization parameter (g) of 0.197. Additionally, a notable increase of 53.6 % was observed in hydrogen yield. The results indicated that catalytic graphitization had the potential to enhance the economic benefit and carbon reduction by up to 2081 % and 190 %, respectively, in comparison to pyrolysis. This study offers insight into an economically and environmentally friendly refining technology for old corrugated containers and the development of more sustainable processes utilizing waste organics as a carbon precursor for the production of graphitic carbon.